This invention relates to a locking mechanism for a safe door. In particular, this invention relates to a locking mechanism that includes a vertical lock plate and a live bolt lock plate that are coupled to one another in such a way that movement of one of the plates causes movement of the other plate irrespective of whether the plates are coupled with a drive mechanism.
Mechanisms for locking safe doors are well known in the art. One of these locking mechanisms generally includes a drive gear, a live bolt lock plate coupled with at least one locking pin, a primary vertical lock plate, and a tumbler stack. The drive gear operates to couple the live lock bolt plate with the primary vertical lock plate and is the principal mechanism for moving the plates relative to one another. In particular, as the drive gear is rotated, the live bolt lock plate moves along a linear path to engage and disengage the locking pins with the safe housing, and the primary vertical lock plate moves in a direction that is perpendicular to the movement of the live bolt lock plate when the notches in the tumbler stack are aligned. When the notches in the tumbler wheel are not aligned, the primary vertical lock plate is not permitted to move, thereby preventing the drive gear from moving the live bolt plate and locking pins to an unlocked position.
The use of the drive gear as the primary mechanism for coupling and moving the live bolt lock plate and the primary vertical lock plate relative to one another presents a number of drawbacks and deficiencies. For instance, an unauthorized attempt to open the safe door may be made by bypassing the locking mechanism. One way to bypass the lock mechanism is to displace the drive gear in such a way so that the drive gear is no longer aligned with the primary vertical lock plate. When the drive gear is no longer in alignment with the vertical lock plate and the drive gear is rotated, the primary vertical lock plate will not move since the drive gear and vertical lock plate are no longer engaged. At this point, the live bolt lock plate may be manipulated in such a way to disengage the locking pins from the safe housing without having to worry about whether the tumbler stack will permit the primary vertical lock plate to move into an unlocked position. In other words, the primary vertical lock plate and the tumbler stack no longer play an active part in locking the safe since they are not connected with the drive gear and the live lock bolt plate.
Accordingly, there exists a need for a locking mechanism where the live bolt plate and primary vertical lock plate are coupled together in such a way where movement of one plate causes movement in the other plate regardless of whether the drive gear is engaged with both of the plates. The present invention fills these needs as well as other needs.